For rescue hamsters, try these links too
http://www.pet-rescue.org.uk/forums/
http://www.animalrescuers.co.uk/
http://www.rescuerehoming.co.uk/
The RSPCA may be able to put you in touch with a local small animal rescue if they don't have hammies themselves.
It's also worth contacting the South of England Hamster Club and the Southern Hamster Club for breeders in your area or for any rescues that they may know of, and Towy Vale Hamstery who run a national hamster rescue list.
I know there have been some big hamster rescues recently so the hammies are out there, it's just a matter of whether you can get to them.